Telegraphy



April 28, 1925. 1,535,244

H. s. PERCIVAL TELEGRAPHY Filed May 20, 1920 Lille I] ;NVENTOR J0Sikrcwa ATTORNEY Patented Apr. 28, 1925.

UNITED STATES PATENT OFFICE.

HARRY S. PERCIV'AL, 01E BLOOMFIELD, NEW JERSEY, ASSIGNOR TO AMERICANTELE- PHONE AND TELEGRAPH COMPANY, A CORPORATION OF NEW YORK.

"IELEGRAPHY.

Application filed May 20,

To all whom it may concern:

Be it known that I. HARRY S. PERCIVAL. residing at Bloomfield, in thecounty of Essex and State of New Jersey, have invented certainImprovements in Telegraphy, of which the following is a specification.

This invention relates to telegraphy, and it is concerned particularlywith telegraph systems in which transmission is limited to one directionor the other at a time, which systems are generally designated in theart as sin le telegraph systems.

In the single telegraph systems now in common use the line relays are ofthe type which is responsive to the )resence or ab sence of line currentIIfI'QSPO tIv'Q of the dire tionthereof. Systems of this character aretroublesome, when used on long lines, due to leakage and capacity. Insuch instances it is not uncommon to employ a duplex telegraph systemmodified for one-way operation, the a dvantage of this system being thatit employs relays responsive to the direction of current, as forexample, relays with polarized armaturcs. The duplex systems, however,necessitate the use of balancing artificial lines and other equipmentwhich is expensive to install and troublesome to keep in adjustment.

The object of the present invention is to provide a single telegraphsystem which employs relays of the type responsive to current reversals,thus securing the operating advantages of these relays for the singlesystems without the use of balancing artificial lines and similarequipment.

The invention proposes, furthermore, to provide the line circuit withtwo branches at. each station, one being employed for the transmission,the other for the reception of signals. A translating device is providedat each station to connect one or the other branch to the line accordingas the operator thereat is transmitting or receiving. This translatingdevice is arranged to disconnect the transmitting branch from the linewhen the operator at the distant end isbreaking the message.

A good understanding of the invention may now be had from the followingdescription thereof having reference to the accompanying drawing inwhich:

1*1gure l is a (hagrzmmiatic view of one 1920. Serial No. 382,972.

form and arrangement of apparatus em hodying the invention, and

Figs. 2 and 3 are views showing modific tions of the apparati'ls of Fig.1.

Similar characters of reference designate similar parts in each of theseveral views.

In Fig. l, I have shown a telegraph line with which are associatedstations X. and Y, the former of which comprises a relay 13, thearmature of which is connected to the line, the front contact of whichis associated with a transmitting branch circuit, and the back contactof which is connected with a receiving branch circuit. The transmittingbranch circuit comprises positive and negative battery governed by thearmature of the transmitting relay D, and a relay C, the winding ofwhich is in series with the branch circuit so that the relay isenergized. when current of either positive or negative polarity flowsfrom the transmitting branch into the line. The receiving branch of theline circuit extends from the back contact of the relay B, through thewinding of a polarized relay A to ground. The armature of this relaygoverns a local circuit which comprises battery H, the relay E, thecontact 1 of the polar relay A, the transmitting relay 1), the key K andthe sounder S. The station Y is provided with similar apparatusdesignated by like reference characters, a prime mark being used todistinguish the apparatus of Y from that of X.

The interrelations of the various relays and circuits of this system maybe readily understood from the following description of the operationthereof, in which description the operator at Y is assumed, first, to besending to X. In the course of such sending, relay B will have itsarmature against its front contact and relay B will have its armatureagainst its back contact, all shown in the drawing. If for any reasonthese armatures should be in any other position when the operator at Ybe gins to send, they will at once be thrown to the positions shown uponfirst opening the key K to spacing position. This will appear in thecourse of the description of the operation that follows. Vith the key atY closecL- current flows from the battery H, through'the local circuit,so that relays E and D and the sounder S are energized.

The armature of the relay D is therefore in engagement with the frontcontact. so that current from negative battery flows in the circuitwhich extends through the relay C, the armature of relay B, the line.the armature of relay B and the receiving relay A to ground. Thiscurrent energives the relay C and causes the same to hold closed atcontact 7 the circuit of the relay B so that the armature oi this re ayremains in engagement with its front contact. The negative currentthrough the receiving relay A causes this relay to close the contact 1so that current flows through the local circuit at this station andenergizes the sounder thereat. It is thus seen that when the key at Y isclosed. the sounder-s at both stations are energized. denoting a markingsignal.

To send a spacing signal the operator at 1' opens his key and causes,thus, the release of his sounder and the deenergization of histransmitting relay D. This \anscs tl flow of current from positivebattery through the main line circuit. so that relays U and A areenergized by current 01 opposite direction. The relay C is soconstructed with slow release that it does not open its tront contactduring the reversal of current in its winding; it therefore retains therelay 13 energized so that the same does not open the connection betweenthe main line and the transmitting branch thereof at station Y. Thepolarized receiving relay A responds to the reversal of current byopening its contact 1 and closing contact 2. This takes battery H offthe sounder S so that the same is released, thus causing a spacingsignal at station X. hen the operator at Y recloses his key. he causesanother reversal of current in the main line and a renewcd response. ofthe sounders at both stations. Messages may therefore be transmittedfrom Y to X by operations of the key at Y in the usual manner.

It now, the operator at X desires to break the message from. 1' for thepur pose of sending in the opposite direction, he opens his key so thatduring the interval in which the operator at Y holds his key depressed,current is taken otl the relays l) and E, and from the. sounder S. Thedeenergizationl of E brings about the closure of the circuit of Bthrough the back contact oi. E. so that relay B opens the connection ofthereceiving relay A to the line. and closes that ot' the transmittingbranch c ircuit. The transmitting relay D. having been de energized.connects negative battery through relay (l to the line. Battery of likepolarity. however. is applied to the opposite end of the line so thatcurrent ceases to flow therein. The relay C at Y is thustlQ-Qlltl'iljlZQtl and opens its contact so that relay l5 opens theconnection between the line and the transmitting branch circuit ol' Yand closes that to the receiving branch. As this connection is made.current from the negative battery at X flows through the relay thearmature of the relay ll. and through the line to station Y. where itflows through the armature of relay 15 and the winding of the polarizedreceiving relay A. to ground. The current in this circuit energizes therelay so that the same operates its arn'iature into engagement with itsfront contact and maintains the circuit ol l3 closed. The negativecurrent through relay A causes the same to close its contact 2. thustaking the battery H off the transmitting relay 1) and the sounder S.which thus notifies the operator at Y that X is breaking his message. llil oreover. ii the operator at Y continues to operate his key he willfail to note a. response in his sounder because battery is oh the key.Having thus become aware that X is interrul'iting him. he closes his keyand takes the message from X. which is transmitted to Y in the samemanner as hereinetore explained for transmission in the oppositedirection.

The foregoing explanation of breaking by the operator at X shows how anoperator gets control of the line by opening his key. It for any reasonthe arn'iaturcs ot relays ll and B should both be on their back contactswhen the line as idle. or it these armatures were reversed from thepositions shown in Figure l. in either case they would go to thepositions there shown upon first opening the, key at K. 'l hereal terthe operation of sending would be. as heretolore described.

It will have been noted that the relay E is included in the localcircuit at each station. so that this relay closes and opens its contactwhen the operator thereat is transmitting. These operations of thecontact have no ellcct. however, on relay 3 -lor the reason that thecircuit thereot' is maintained closed by the relay C while the circuitthereof is connected to the line. The purpose, for which the relay E isprovided is to close the circuit of the adjacent relay Bwhen theoperator at the same station is breaking. as hereinbctore explained. Toprevent an operalion of E when the operator is receiving, the contact 2of the receiving relay is connected through a resistance R to theground, (reference being had to station X) so that the current frombattery H energizes the relay 1*) in either position of the arinatureot' relay A, relay I) being slow enough in release to hold during thechange from one of said positions to the other. A similar circuit isprovided for relay E ot station Y.

in the modification illustrated in Fig. 2, l elin'iinate one of therelays employed in the preceding lorm ol embodin'lent ol the invention.The relay ll governs. as before,

lllll ployed during reception consists of the One of these, the pathused during transmission, extends from the battery M through the frontcontact of relay C, the key K, the transmitting relay D and the sounderto ground. The other of these paths-embattery M, back contact of relayC, the winding of relay B, the armature of relay A, the key K, relay Dand the sounder, to ground.

The operation of this modification with X receiving and Y sending is asfollows: It is assumed that the armatures of relays B and B are in thepositions shown in Figure if not, they will be brought to thosepositions by first opening the key at Y, as

will appear in the course of the following description. hen the key at Yis closed, relay D and the sounder are energized by current from batteryM. The. front contact of relay D associates negative battery with thetransmitting branch circuit so that current of this polarity flows overthe line. and operates the arn'iature of the receiving relay A atstation X to the position shown in the drawing. Current therefore flowsthrough the receiving path of the local circuit at station X, whichcurrent energizes the relay B and the relay D as well as the sounder,the position of which thus corresponds to the position of that at Y.\Vhen the key at Y is opened to send a spacing signal, the sounder S isdeenergized and the current in the line is reversed. This causes thereceiving relay A to closeits contact 2, thus opening the soundercircuit to give the spacing signal. The relay 1% remains energized bycurrent which flows through the resistance It to ground. This relayserves, thus, to hold to the receiving branch circuit. connected to theline at station X. The relay B at station Y remains tie-energized duringthe transmission of the message because the circuit of this relay isheld open at the back contact of relay 0.

If the operator at X wants to break the message from Y, he opens his keyso that during the interval in which the operator at Y holds his keydepressed the relay 1% is (lo-energized and closes its back con tact andthe relay D is (lo-energized and associates negative battery with theline circuit. Current therefore ceases to flow in the main line and therelay C, in closing its back contact, causes the energization of relay Bso that the same connects the receiving branch circuit to the line.Negative current now flows from stationv X through the relay C, over theline, and through the receiving relay A to ground. Relay C is thusenergized and in closing its front contact establishes the transmissionpath of the local circuit at X. The relay A of Y reverses its armatureand opens the circuit of the sounder. Current is thus taken oft the keyat station Y, and the operator is thus notified that he is beinginterrupted by station X. He closes his key and the operator at X isfree to send to Y.

In the modification of the invention shown in Fig. 3, the number ofrelays is the same as in the preceding modification, and the 10- calcircuit at each station is again made up of two paths, the transmissionpath extending from the battery M through the front contact of the relayC, the armature of the receiving relay A, the winding of thetransmitting relay D and the sounder to ground; and the receiving pathextending from the same battery, through the winding of'the relay B,armature of the receiving relay A, transmitting relay D and the sounder,to ground. The operation of this arrangement with Y sending to X is asfollows: It is assumed that the armatures of relays B and B are in thepositions shown in Figure. 3; if not, they will be brought to thosepositions by first opening the key at Y, as will appear in the course ofthe following description. ith the key at Y closed, nega tive currentflows through the relay C and over the line to station X, where itcausesthe receiving relay A to close its upper con tact, so that current frombattery M flows through the receiving path of the local circuit X.Opening the key at Y reverses the direction of the current in the linecircuit, so that the receiving relay A opens the sounder circuit, butretains the relay B energized by current flowing through the contact 2and resistance R to ground. Relay B thus maintains its lower contactclosed while signals are being received at the station X. The relay C atY, being energized by the line current, holds the transmitting path ofthe local circuit closed. The front contact of C is in shunt to therelay B, which is therefore (lo-energized while current continues toflow in the transmitting branch circuit.

lVhen the operator at X, in order to break the message from Y, opens hiskey so that the relays B and D are tie-energized, he causes negativebattery to be applied to the line so that current ceases to flow therein. This brings about the de-energization of the relay C at station Y,which in turn causes the removal of the short circuit from the windingof relay 3, so that the same is energized and connects the line to thereceiving relay A of station Y. Negative current now flows over the linecircuit and causes the receiving relay A to open contact 1 and closecontact 2. "his takes battery ott the key at Y and serves to notify theoperator at this station that X is breaking his message. He, therefore,leaves the key in its closed position and receives the message in theregular manner.

Although i have shown and described herein only a few terms ofembodiment of the invention, it is readily understood that various otherchange, and modifications may be made therein within the scope of thefollowing claims, without departing from the spirit and scope of theinvention.

'hat I claim is:

1. In a telegraph system, a main line, a station associated therewith, atransmitting branch circuit for said main line at said station, a devicetor at times associating said main line with said branch circuit, atransmitting device at said station, means governed by said transmittingdevice for causing said tirst mentioned device to assume its operativeposition and means associated with said transmitting branch circuit toretaining said device in its operative position.

2. in a telegraph system, a main line, a plurality ot stationsassociated therew th. a transmitting and a receiving branch circuit forsaid main line at each of said stations, a translating device at eachstation for assoc'ating one or the other branch circuits with said mainline, a key tor transmitting and a sounder tor receiving, both. inseries in a single circuit with respect to one and the same battery ateach station, means controlled by said key for causing the adjacenttranslating device to assume one or the other of its positions accordingto the position or the key, and means effective when the keys at saidstations are in predetermined relative positions tor rendering thetranslating device of one station non-responsive to its key.

In a telegraph system, a line, a plural ity of stations associatedtherewith, a set of receiving and a set of transmitting device for saidline at each station, means at each station for connecting one or theother of said sets with said line, and means operable at each stationfor rendering the said connecting means ineffective at the other stationwhen said other station is transmitting and a transmitter and a receiverin series in one circuit at -ta -h station and acted on respectively bysaid transmitting and receiving devices.

4;. in a telegraph system, a main line, a station associated therewith,a transmitting and a receiving branch for said line at said station, andmeans selectively actuated when said station is transmitting orreceiving for associating said transmitting or receiving branch,respectively, with said line and :1

transmitter and a receiver in series in one circuit at each station andacted on respectively by said transmitting and receiving branches.

In a telegraph system, a main line, a plurality of stations associatedtherewith, a receiving branch and a transmitting branch for said mainline at each of said stations, relay for each station arrai'iged toassociate one or the other of said branch circuits with the main lineaccording to its operated or non-operated position, a key and sounder ateach station, a polarized receiving relay associated with said receivingbranch circuit for causing operations ot' said sounder in accordancewith the direction of current in. the main line, a source of current, atransmitting relay responsive to said key for associating positive ornegative potential. with said transmitting branch circuit according tothe position of said hey, a relay at each station responsive to thetransmitting key thereat tor causing an initial operation of said firstmentioned relay, and a device associated with the transmitting branchcircuit at each station tor retaining said first mentioned relay inoperated position when current flows through said branch circuit.

(3. In combination, a main line, a station associated therewith, a localcircuit at said station, said circuit comprising a transmitting and areceiving path, a transmitting device and a sounder associated with bothof said paths, a transmitting branch and a receiving branch tor saidmain line, a relay associated with the receiving path of the localcircuit for associating one or the other of said branches with said mainline, a receiving relay associated with said receiving branch circuitfor governing said receiving path of the local circuit, and a relayassociated with said transmitting branch of the main line circuit forgoverning both of said paths of the local circuit.

7. In a telegraph system, a line, a plurality of stations associatedtherewith, a transmitting and a receiving branch for said line at eachstation, a translating device at each station for associating one or theother oi said branches with said line, a key at each station, a relayresponsive to tlow of current in said transmitting branch, a circuit forsaid translating device governed by said key and said relay, a receivingrelay associated with said receiving branch, and a circuit governedthereby for attimes rendering said translating de vice non-responsive tosaid key.

8. In a telegraph system, a line, a plurality of stations associatedtherewith, a transmitting and a receiving branch for said line at eachstation, a translating device at each station for associating one or anda circuitgoverned thereby for at times rendering said relaynon-responsive to said key.

In testimony whereof, I have signed my name to this specification this14th day of.

May 1920.

HARRY s. PERCIVAL.

